He will say the changes are needed to turn off the “magnetic pull” of Britain’s benefits system while attacking Labour’s “open door” which let some 2.5million migrants enter the country.

Writing in a newspaper article, the Prime Minister will say: “As Peter Mandelson has admitted, they were practically sending out ‘search parties’ for people to come here. There was a failed points system, which allowed so-called ‘highly-skilled’ workers to come here for up to three years to look for work – and often they ended up stacking shelves.

We will be reducing that cut-off point to three months, saying very clearly: you cannot expect to come to Britain and get something for nothing

David Cameron

“There was an increasingly generous, no-questions-asked welfare system that drew migrants to Britain for the wrong reasons. And unforgivably, while we had the highest rates of migration in our modern history, we also had well over five million people of working age on out-of-work benefits.”

Mr Cameron will add: “We’re also making sure people come for the right reasons – which has meant addressing the magnetic pull of Britain’s benefits system. We changed the rules so no-one can come to this country and expect to get out-of-work benefits immediately; they must wait at least three months.

“And we are announcing today that we are cutting the time people can claim these benefits for. It used to be that European jobseekers could claim JSA or child benefit for a maximum of six months before their benefits would be cut off, unless they had very clear job prospects.

“We will be reducing that cut-off point to three months, saying very clearly: you cannot expect to come to Britain and get something for nothing. This is about building a different kind of Britain – a country that is not a soft touch, but a place to play your part; a nation where those who work hard can get on.”

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Anyone earning £150 a week, equivalent to working 24 hours on the minimum wage, will be classed as a worker.

Those earning less and claiming benefits will be interviewed to see if they have a genuine prospect of work. If they fail, they will be classed as “marginal and ancillary” and may be sent home.

If language is a barrier to employment, claimants will be given six months to improve their communication skills.

The move is likely to delight Tory backbenchers and campaigners who want to cut the amount of taxpayers’ cash handed over in benefit payments.

Jonathan Isaby, chief executive of the TaxPayers’ Alliance, said: “Migrants coming to the UK to work hard and make a life for their families should be welcome, but we must also ensure that the bloated welfare budget is brought under control.”

The measures are expected to aid Tory plans to cut net immigration to under 100,000 a year. Official figures show it rose from 177,000 in 2012 to 212,000 in the year to December.

A recent survey found there were 611,779 unemployed EU migrants living in the UK.